void swap(int *x, int *y) {
    int temp;
    temp = *x;
    *x = *y;
    *y = temp;
    printf("In swap: %d %d\n", *x, *y);
}
 
int main() {
    int a = 10;
    int b = 20;
    swap(&a, &b);
    printf("After swap: %d %d\n", a, b);
    return 0;
}